1. Field of the Invention
The invention relates to a self-propelled construction machine, in particular a road milling machine or a slipform paver, which has a chassis having front and rear wheels or running gears in the working direction, a drive device for driving the front and rear wheels or running gears, and a working device, the construction machine being able to carry out translational and/or rotational movements on the terrain and to install structures on the terrain or to alter the terrain in a predetermined working region. The invention further relates to a method for controlling a self-propelled construction machine.
2. Description of the Prior Art
Various types of self-propelled construction machines are known, including in particular the known road milling machines or slipform pavers. These construction machines are distinguished in that they have a working device for installing structures on the terrain or for altering the terrain.
In the known road millers, the working device comprises a milling roller which is equipped with milling cutters and with which material can be milled away from the road surface. The slipform pavers have a device for moulding fluid material, in particular concrete, which is also referred to as a concrete trough. The concrete trough allows structures of various designs to be produced, for example guiding walls or gutters.
When planning and carrying out the building project using the known construction machines, the problem arises whereby objects already present in the terrain, e.g. drains or manhole covers, have to be taken into account. The structure should, for example, not be located on top of a drain, or material should not be milled away from the region of the terrain in which for example a manhole cover is located.
To take account of objects present in the terrain, an intervention has to be made in the machine control. For example, when travelling over a manhole cover, the milling roller of a road milling machine has to be raised relative to the surface to be altered from a predetermined position, taking into account a margin of safety within a predetermined route, which is dependent on the dimensions of the manhole cover. In practice, however, the machine operator cannot see the exact position of the manhole cover at the level of the milling roller since the milling roller is below the cab. Therefore, in practice, the position of a manhole cover in the terrain is marked by lateral lines which are visible to the machine operator or to another person. However, marking objects present in the terrain proves to be disadvantageous in practice. Firstly, marking the objects necessitates an additional work step. In addition, it is difficult to draw the lines at a precise right angle to the direction of travel. Moreover, in darkness, the lines cannot be seen or can only be seen with difficulty. Furthermore, it is not easy to mark the objects when it is raining. Owing to the lack of accuracy, it is therefore necessary to select a relatively high margin of safety, which makes more extra work necessary.
When altering the terrain or installing structures on the terrain, the problem also arises of controlling the movement of the construction machine on the terrain while taking into account objects present in the terrain. For example, the construction machine should move at a predetermined distance along a curb to the side thereof.
Various devices for controlling construction machines which aim to make the works easier to plan and carry out are known.
DE 10 2010 048 185 A1 describes a device for making it easier to maneuver a manually controlled construction machine on the terrain, which machine detects, by means of sensors, the steering angle of the running gears as set by the machine operator. The maneuvering device then calculates the trajectories describing the route of the construction machine, which are displayed to the machine operator on a display unit.
EP 2 336 424 A2 describes a self-propelled construction machine which has a unit for determining data describing a target curve in a reference system which is independent of the position and orientation of the construction machine, and a control unit which is designed such that a reference point on the construction machine moves on the target curve starting from a predetermined starting point at which the construction machine has a predetermined position and orientation on the terrain.
EP 2 719 829 A1 discloses a method for controlling a construction machine, in which the data describing a target curve in a reference system which is independent of the position and orientation of the construction machine are determined by means of a measuring apparatus (rover) on the terrain and input into a working memory of the construction machine.
US 2009/0016818 A1 and US 2012/0001638 A1 describe construction machines which have a device for detecting metal objects which may be located below the terrain surface. If an object made of metal is detected, the road milling machine can be stopped or the milling roller can be raised. The objects buried in the terrain can be detected by a metal detector.